Psychiatric comorbidity in adolescent electronic and conventional cigarette use.

The popularity of electronic (e-) cigarettes has greatly increased recently, particularly in adolescents. However, the extent of psychiatric comorbidity with adolescent e-cigarette use and dual use of conventional (combustible) and e-cigarettes is unknown. This study characterized psychiatric comorbidity in adolescent conventional and e-cigarette use. Ninth grade students attending high schools in Los Angeles, CA (M age = 14) completed self-report measures of conventional/e-cigarette use, emotional disorders, substance use/problems, and transdiagnostic psychiatric phenotypes consistent with the NIMH-Research Domain Criteria Initiative. Outcomes were compared by lifetime use of: (1) neither conventional nor e-cigarettes (non-use; N = 2557, 77.3%); (2) e-cigarettes only (N = 412, 12.4%); (3) conventional cigarettes only (N = 152, 4.6%); and (4) conventional and e-cigarettes (dual use; N = 189, 5.6%). In comparison to adolescents who used conventional cigarettes only, e-cigarette only users reported lower levels of internalizing syndromes (depression, generalized anxiety, panic, social phobia, and obsessive-compulsive disorder) and transdiagnostic phenotypes (i.e., distress intolerance, anxiety sensitivity, rash action during negative affect). Depression, panic disorder, and anhedonia were higher in e-cigarette only vs. non-users. For several externalizing outcomes (mania, rash action during positive affect, alcohol drug use/abuse) and anhedonia, an ordered pattern was observed, whereby comorbidity was lowest in non-users, moderate in single product users (conventional or e-cigarette), and highest in dual users. These findings: (1) raise question of whether emotionally-healthier ('lower-risk') adolescents who are not interested in conventional cigarettes are being attracted to e-cigarettes; (2) indicate that research, intervention, and policy dedicated to adolescent tobacco-psychiatric comorbidity should distinguish conventional cigarette, e-cigarette, and dual use.